The present invention relates to a video signal storage apparatus for the NTSC system which stores a digitized NTSC video signal and which is suited for use in a video signal special effect apparatus.
By using a video signal apparatus, it has been attempted to produce many special picture effects by controlling writing addresses or reading addresses of the video signal storage apparatus while suppressing, compressing and expanding, for example. In this case, conventionally, it is impossible to directly carry out interpolation processing or the like processing between two adjacent lines and between two adjacent television frames having the composite signal form since the phase of the color subcarrier is different between the two adjacent lines and between the two adjacent frames. Therefore, according to the prior art, a composite video signal is separated into three component signals, i.e., a luminance (Y) signal, an I signal and a Q signal, and, then processing, such as interpolation processing, is individually carried out on each component signal. In this case, the I and Q signals constitute the components of a chrominance (C) signal. Thereafter, the processed component signals are encoded and recombined into the composite signal form.
As described above, according to the prior art, since the color subcarrier in the composite video signal has a different phase in the two adjacent lines and frames, it is necessary to use three independent memory configurations for the Y, I and Q signals when such computation processing between two adjacent lines or between two adjacent frames is required.